This application claims benefit of priority to Japanese Patent Application No. 11-192081 filed Jul. 6, 1999, the entire content of which is incorporated by reference herein.
1. Field of the Invention
This invention relates to an active guide system guiding a movable unit such as an elevator cage.
2. Description of the Background
In general, an elevator cage is hung by wire cables and is driven by a hoisting machine along guide rails vertically fixed in a hoistway. The elevator cage may shake due to load imbalance or passenger motion, since the cage is hung by wire cables. The shake is restrained by guiding the elevator cage along guide rails.
Guide systems that include wheels rolling on guide rails and suspensions, are usually used for guiding the elevator cage along the guide rails. However, unwanted noise and vibration caused by irregularities in the rail such as warps and joints, are transferred to passengers in the cage via the wheels, spoiling the comfortable ride.
In order to resolve the above problem, various alternative approaches have been proposed, which are disclosed in Japanese patent publication (Kokai) No. 51-116548, Japanese patent publication (Kokai) No. 6-336383, and Japanese patent publication (Kokai) No. 63-87482. These references disclose an elevator cage provided with electromagnets operating attractive forces on guide rails made of iron, whereby the cage may be guided without contact with the guide rails.
Japanese patent publication (Kokai) No. 63-87482 discloses a guide system capable of restraining the shake of the elevator cage caused by irregularities of the guide rails by controlling electromagnets so as to keep a constant distance from a vertical reference wire disposed to be adjacent to the guide rail, thereby providing a comfortable ride, and reducing a cost of the system by getting rid of an excessive requirement of accuracy for an installation of the guide rails.
However, in the present guide system for elevators as described above, there are some following problems.
The vertical reference wire may be easily set up in case of low-rise buildings having a relatively short length hoistway for an elevator, while it is difficult to fix the vertical reference wire in a hoistway so as to be adjacent to guide rails in case of high-rise buildings or super high-rise buildings recently built and appeared. Further, after fixing the vertical reference wire, the vertical reference wire itself often loses its linearity because of a deformation by an aged deterioration of buildings or an influence of thermal expansion. Therefore, it causes a problem that a lot of time and cost is needed for maintaining the fixed vertical reference wire. Furthermore, electromagnets may not be excited in advance against irregularities on the guide rails, since a vertical position of the cage cannot be detected by using the vertical reference wire. Accordingly, a vibration restraining control may not start to run until a position relationship with the vertical reference wire goes wrong due to the irregularities. As a result, a certain extent of shaking may not be restrained in view of the principle. Therefore, there is a limit to improving a comfortable ride in this system.
Accordingly, one object of this invention is to provide a guide system for an elevator, which improves a comfortable ride by effectively restraining the shake of an elevator cage.
Another object of the present invention is to provide a minimized and simplified guide system for an elevator.
The present invention provides a guide system for an elevator, including a movable unit configured to move along a guide rail, a beam projector configured to form an optical path of a light parallel to a moving direction of the movable unit, a position detector disposed on the optical path and configured to detect a position relationship between the optical path and the movable unit, and an actuator coupled to the movable unit and configured to change a position of the movable unit by a reaction force, caused by a force operating on the guide rail on the basis of the output of the position detector.